Concrete saw having multiple motors

ABSTRACT

A device comprises an implement configured to be driven and a first motor and a second motor. Each motor includes a rotational output shaft and a transmission assembly connected to the output shaft. The output shafts of the first and second motors are coupled together by the transmission assemblies such that the output shafts turn at the same rate. The first and second motors contribute equally to the driving of the implement.

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 61/383,907 filed on Sep. 17, 2010 and U.S.Provisional Patent Application Ser. No. 61/411,941 filed on Nov. 10,2010, both applications being incorporated herein in their entirety.

BACKGROUND

Exemplary embodiments herein generally relate to a device including animplement driven by at least two motors, and more particularly, to aself-propelled operator-guided or steerable concrete saw having parallelmotors.

In the concrete industry, when building bridges, buildings, roads andthe like, it is often necessary to pour large horizontal slabs ofconcrete. Once poured, it is usually necessary to machine the slab. Suchmachining may include cutting seams completely through the slab (to formexpansion joints and to allow for foundation shifting), cutting notchespartially into the slab (to create stress cracks along which the slabwill split), cutting multiple grooves into the slab to create a highfriction surface such as for bridges, grinding the surface of the slaband the like. Concrete saws are also used in the demolition or removalof concrete, such as during the sawing and replacement of bridge decks.Various types of concrete saws may be utilized to carry out thesemachining and demolition tasks. In larger industrial applications, largeself-propelled saws are used that are powered in a variety of manners,such as by gasoline, diesel, electric, propane and natural gas enginesmounted on the saw. While performing a cut, the operator controls thedirection, cutting speed, cutting depth and the like.

Conventional concrete saws include a gasoline, diesel, propane (internalcombustion), hydraulic and air or electric engine aligned along an axistransverse to the longitudinal axis of the saw frame. This transversearrangement aligns the engine crankshaft parallel to the rotational axisof the saw blade, to afford an easy design for interconnecting pulleysupon the crankshaft and the saw blade. Recently designed concrete sawsinclude an engine that is mounted with its longitudinal axis in linewith the longitudinal axis of the saw. This is in contrast totraditional transverse mounting arrangements. This new arrangementallows the saw to be easily moved through doorways and other passagesthat were previously not passable. However, because concrete sawsrequire large values of torque and power (for example, at least 70 hp),the single engine for both layouts is a large engine, and hence a morepowerful engine. One drawback to the use of a single large engine forthe concrete saw is the high cost of such an engine. Another drawback ofthe single large engine for the concrete saw is an increase in theoverall weight of the concrete saw which can make the saw morecumbersome to maneuver.

BRIEF DESCRIPTION

In accordance with one aspect, a device comprises an implementconfigured to be driven and a first motor and a second motor. Each motorincludes a rotational output shaft and a transmission assembly connectedto the output shaft. The output shafts of the first and second motorsare coupled together by the transmission assemblies such that the outputshafts turn at the same rate. The first and second motors contributeequally to the driving of the implement.

In accordance with another aspect, a concrete saw comprises a generallyrectangular frame having a front end, a read end and a longitudinallength. A first motor and a second motor are supported by the frame.Each motor includes a rotational output shaft aligned generallytransverse to the longitudinal length of the frame and a sprocketassembly connected to the output shaft. The output shafts of the firstand second motors are coupled together by the sprocket assemblies suchthat the output shafts turn at approximately the same rate. The firstand second motors contribute equally to the driving of a saw blade. Thesaw blade is rotatably connected to the frame via a saw blade shaftoriented parallel to the outputs shafts of the first and second motors.The saw blade shaft has at least one sheave pulley. A rotatable jackshaft is oriented parallel to the outputs shafts of the first and secondmotors. The jack shaft has a sprocket and at least one sheave pulley.The sprocket is operably connected to one of the sprocket assemblies ofthe first and second motors. The at least one sheave pulley is operablyconnected to the at least one sheave pulley of the saw blade shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a left side perspective view of an exemplary device, such as aconcrete saw, having multiple motors according to one aspect of thepresent invention.

FIG. 2 is a right side perspective view of the concrete saw of FIG. 1.

FIG. 3 is an enlarged perspective view of the parallel motors of theconcrete saw of FIG. 1.

FIG. 4 is an enlarged perspective view of a sprocket assembly of one ofthe motors and a sprocket and a sheave pulley of a drive shaftassociated with a saw blade of the concrete saw of FIG. 1.

FIG. 5 is an enlarged front prospective view of the concrete saw of FIG.1.

FIGS. 6 and 7 are side perspective views of the concrete saw of FIG. 1in a tilted position.

FIG. 8 is a schematic view of another exemplary device including animplement driven by multiple motors according to another aspect of thepresent invention.

FIGS. 9 and 10 schematically depict exemplary manners for controllingoperation of the multiple motors of FIG. 8.

DETAILED DESCRIPTION

It should, of course, be understood that the description and drawingsherein are merely illustrative and that various modifications andchanges can be made in the structures disclosed without departing fromthe present disclosure. It will also be appreciated that the variousidentified components of the exemplary concrete saw disclosed herein aremerely terms of art that may vary from one manufacturer to another andshould not be deemed to limit the present disclosure.

Referring now to the drawings, wherein like numerals refer to like partsthroughout the several views, FIGS. 1-7 illustrate an exemplary devicehaving multiple motors, such as a concrete saw 100 for cutting seams,notches and/or grooves into or through asphalt, concrete, stone or othersimilar surfaces concrete, asphalt, stone and other hardened surfacesaccording to the present disclosure. The concrete saw 100 includes animplement or blade 102, at least two engines or motors 104,106 fordriving the saw blade 102, a frame 108 for supporting the at least twomotors and a set of front wheels 110 and rear wheels 112. The saw 100 ispreferably a self-propelled saw, and thus the rear wheels 112 are drivenin a conventional manner (e.g., a hydraulic drive system or other likesystem). However, it will be appreciated that saw 100 could be apush-type saw. The concrete saw 100 is shown having the two motors104,106; although, more than two motors are contemplated. It will alsobe appreciated that the at least two motors 104,106 may comprise agasoline, diesel or propane (internal combustion) engine, hydraulic andair engine, or an electrical motor.

The concrete saw 100 also includes operational systems that are known orconventional in the art. These systems include a locomotion system thatdrives the rear wheels 112 supporting the saw frame 108 at a desiredspeed. A lift system 120 is also included that is able to tilt the sawframe 108. When tilted the saw blade 102 may be taken out of contactwith the substrate being cut (see FIGS. 6 and 7). The concrete saw 100can include an engine mounting system that minimizes vibration withinthe frame. The saw also includes at least one speed selection lever 128for controlling the speed of advancement of the saw. Additionally, theconcrete saw 100 can includes some type of dampening mechanism thatinterrupts direct communication between the at least two motors 104,106and saw blade 102 when the blade encounters significant predeterminedresistance.

With particular reference to FIGS. 1-3, the motors 104,106 arepositioned in parallel, side by-side relationship on the frame 108 andare of a type generally known in the art. With this parallelrelationship, each motor 104,106 is oriented with its respective drivenoutput shaft or crankshaft 140,142 generally perpendicular to an axisdefined by the length of the frame 108. This transverse arrangementaligns the output shafts 140,142 parallel to the rotational axis of thesaw blade 102, to afford an easy design for interconnecting pulleys uponthe output shafts and the saw blade. However, unlike the prior artconcrete saw having a similar transverse arrangement, the use of thesmaller motors 104,106 allows the concrete saw 100 to be easily movedthrough doorways and other narrow passages.

As indicted previously, the known concrete saw typically requires asingle seventy horsepower (70 hp) motor to drive the saw blade. In orderto provide similar torque and power values as the 70 hp single motor,each motor 104,106 is at least a thirty-five horsepower (35 hp) motor,which when operating in unison provides the necessary torque and powerfor the concrete saw 100. One type of motor for use with the concretesaw 100 is a Briggs & Stratton Vanguard® 35 hp motor; although,alternative motors having a similar torque and power ratings arecontemplated. As is known, these Briggs & Stratton motors 104,106 eachincludes an air cooling system 150, an air cleaner 152 and a muffler154. Further details of the Briggs & Stratton motors 104,106 are knownto one skilled in the art and, as such, are omitted for conciseness.

As best depicted in FIGS. 3-5, the concrete saw 100 includes a drivesystem for transmitting rotational energy from the motors 104,106 to thesaw blade 102. The drive system includes a first drive or jack shaft160, which is oriented substantially parallel with the output shafts140,142, is supported at each end by bearings 162,162 for transmittingpower across the front of the concrete saw 100 and to the saw blade 102.The first jack shaft 160 includes at one end a first multi-sheave pulley170 for driving one or more V-belts 172 and at the other end a secondmulti-sheave pulley 174 for driving one or more V-belts 176. A seconddrive or jack shaft 180 (i.e., saw blade shaft), which is orientedparallel to the first jack shaft 160, is connected to the saw blade 102,and is supported by bearing (not shown) mounted to the frame 108. Thesecond jack shaft 180 includes at one end a third multi-sheave pulley190 and at the other end a fourth multi-sheave pulley 192. As shown, theone or more V-belts 172 are engaged with the first and third sheavepulleys 170 and 190 and the one or more V-belts 176 are engaged with thesecond and fourth sheave pulleys 174 and 192. Located at the fore end ofthe first jack shaft 160 and inside of the first sheave pulley 170 is asprocket 200. In the depicted embodiment, the sprocket 200 and the firstsheave pulley 170 are of different diameters; although, this is notrequired. As shown, sprocket 200 can have a diameter which is abouttwice the diameter of first sheave pulley 170.

The drive system further includes a sprocket assembly 210 provided onthe output shaft 140 of motor 104 and comprises a pair of sprockets 212and 214. Extending between sprocket 200 and sprocket 212 is a flexiblebelt 220. The belt 220 includes a plurality of teeth extending along theinside surface or diameter 222 of the belt 220. The teeth of belt 220engage teeth formed along the outer diameter of the sprockets 200 and212. Similarly, provided on the output shaft 142 of motor 106 is asprocket assembly 230 including a pair of sprockets 232 and 234.Extending between sprocket 214 and sprocket 234 is a flexible belt 240which includes a plurality of teeth extending along the inside surfaceor diameter 242 the belt 240. The teeth of belt 240 engage the teethformed along the outer diameter of the sprockets 214 and 234. Bycoupling the motors 104,106 together such that their respective outputshafts 140,142 turn at the same rate, the motors can contribute equallyto the driving of the saw blade 102 and together provide twice the poweras a single 35 hp motor. This, in turn, provides the necessary 70 hp todrive the saw blade 102. As shown, the sprockets 212,214,234 haveapproximately equal diameters; though it should be appreciated that thesprockets can be of different diameters. Also, the sprocket 200 has adiameter larger than the diameters of the sprockets 212,214,234;although, this is not required. Similarly, it will be appreciated thatmotors of different horsepower may be coupled together in order toprovide a desired combined horsepower. For example, a 50 hp motor and a30 hp motor could be combined to provide a total of 80 hp to drive thesaw blade 102.

With continued reference to FIGS. 1 and 3, operably connected to thesprocket 232 is a flexible belt assembly 250 that powers a conventionalhydrostatic motor that is used to propel the saw. The assembly 250includes a first idler roller or sprocket 252 and a second idler rolleror sprocket 254. Both the first idler roller 252 and the second idlerroller 254 are positioned forward of the sprocket assembly 230, thefirst idler roller being located below the second idler roller. Theassembly 250 further includes an idler arm 260 and a biasing means 262for biasing the arm toward the frame 108. Extending to the hydrostatictransmission is a power belt 256. The arm 260 includes a first end 264pivotally connected to the frame 108 and a second end 266 connected tothe first idler roller 252. The biasing means 262 is operably coupled tothe second end 266 and the frame 108. A bolt 268 that can be loosenedwith a conventional tool, such as a wrench, to allow the arm 260 topivot freely, or tightened to lock the arm 260 into position.

The toothed belts 220,240 may be any number of conventionally availabletoothed flexible rubber belts. However, a preferred belt is a POLYCHAIN®synchronous belt available from the Gates Rubber Company. Suchsynchronous belts resist slipping and they normally do not requirecontinual retensioning. This type of belt does an excellent job oftransferring energy. One synchronous belt can do the job of many V-beltsthereby saving valuable space. The use of a synchronous belt affordsseveral advantages over conventional V-belts. For example, synchronousbelts operate at zero slip and they do not require near the load thatV-belts require for proper tensioning. Lower tension levels reduce loadlevels on shafts, thereby helping to extend bearing life. Enginecrankshafts are especially sensitive to high tension loads. High belttension loads create a bending effect upon the crankshaft which reducesengine life. Generally, engines are designed with light shell typebearing to support the crankshaft. These shell type bearings are notcapable of withstanding major side loads over a substantial period oftime. The use of a synchronous belt, that requires minimal tensioning,avoids all of the excessive loading issues presented by V-belts.

Also, in the present design the one or more V-belts 172,176 are at theend of the respective first and second jack shafts 160,180 therebyfacilitating the replacement of such belts. The configuration alsoallows one to use small pulleys to drive the V-belts 172,176, therebyfacilitating good cutting depths. Use of the jack shafts 160,180 thatextends across the width of the concrete saw 100, along with V-belts172,176 and toothed belts 220,240 also provides an advantage.Specifically, such arrangement minimizes the width of the saw 100,reduces loads on the engine bearings, and because it employs V-belts172,176, it allows for slip in the event that the blade 102 becomestrapped or stalled.

With reference now to FIG. 5, a pair of V-belt tensioner assemblies280,282 can be provided at a forward end of the frame 108. The tensionerassemblies 280,282 provide for positional adjustment, and preferablyvertical adjustment, between the output shaft 140 of motor 104, thefirst jack shaft 160 and the second jack shaft 180. This enablespositional adjustment, i.e. the spacing between the sprocket 200 locatedon the jack shaft and the sprocket 212 located on the output shaft 140,and between the first and second sheave pulleys 170,174 and the thirdand fourth sheave pulleys 190,192. Adjustment of the spacing betweensheave pulleys 170,174 provides for tension adjustment of the one ormore V-belts 172,176 extending between the sheave pulleys.

Each V-belt tensioner assembly 280,282 may be in a variety of differentforms and configurations. In the depicted embodiment, each tensionerassembly 280,282 includes a bolt shaft 290,292 which threadingly engagesan opening of a flange 294,296 extending from a second frame or motormount 300 positioned on the frame 108. Each motor 104,106 and thebearings 162,162 for supporting the first jack shaft 160 are located onthe motor mount 300. Provided along an uppermost end of each bolt shaft290,292 is a bolt head 310,312 configured for engagement by aconventional tool, such as a socket or wrench. A lowermost end 314,316of the each bolt shaft rests upon and is supported by the frame 108. Acorresponding rear set of pivotable engine mounts (not shown) can beprovided along an opposite end of the motors 104,106. Adjustment of thetensioner assemblies provides for vertical adjustment between the frame108 and the motor mount 300.

FIG. 8 schematically illustrates another device 350 according to thepresent disclosure. A shown, the device 350 comprises an implement 352configured to be driven by multiple motors, such as the depicted firstand second motors 354 and 356. Although, more than two motors arecontemplated. The implement 352 can be a cutting implement, a drillingimplement, a hammering implement, a power pack or any other motor drivenimplement. It will also be appreciated that the at least two motors maycomprise a gasoline, diesel or propane (internal combustion) engine,hydraulic and air engine, or an electrical motor.

The device 350 includes a supporting frame 358, a set of front wheels360 and a set of rear wheels 362. The device 350 is preferably aself-propelled device, and thus at least one of the sets of wheels360,362 can be driven in a conventional manner (e.g., a hydraulic drivesystem). However, it will be appreciated that device 350 could be apush-type device. A controller 366 is provided for controlling operationof the device 350, particularly the first and second motors. Thecontroller can be one of mechanically and electrically connected to oneof the first and second motors 354,356. For a self-propelled device 350,the controller 350 can also be connected to the driving means associatedwith the driven set of wheels for controlling operation of the drivingmeans.

In the depicted exemplary embodiment, the first and second motors354,356 are positioned in parallel, side by-side relationship on theframe 358 and are of a type generally known in the art. With thisparallel relationship, each motor 354,356 is oriented with itsrespective driven output shaft or crankshaft 370,372 generallyperpendicular to an axis defined by the length of the frame 358. Thistransverse arrangement provides for a device having a smaller footprintwhich can allow the device 350 to be easily moved through doorways andother narrow passages.

A first transmission assembly 380 is provided on the output shaft 370 ofthe first motor 354. A second transmission assembly 382 is provided onthe output shaft 372 of the second motor 356 and is operably coupled tothe first transmission assembly 370. Similar to the concrete saw 100described above, to connect the first and second motors 354,356together, each of the first and second transmission assemblies 380,382can include at least one sprocket and at least one flexible beltextending between the sprockets. Although, alternative manners forcoupling the motors 354,356 together are contemplated. At least one ofthe first and second transmission assemblies is operably coupled theimplement 325.

By coupling the first and second motors 354,356 together such that theirrespective output shafts 370,372 turn at the same rate, the motors cancontribute equally to the driving of the implement 352 and togetherprovide twice the power as a single motor. It will be appreciated thatmotors of the same or different horsepower may be coupled together inorder to provide a desired combined horsepower. To ensure that theoutput shafts 370,372 turn at the same rate a timing assembly 390 can beoperably coupled to at least one of the first and second transmissionassemblies 380,382. The timing assembly can be part of a central controlof the ignition system of the motors 354,356. As schematically depictedin FIG. 9, and according to one aspect, the timing assembly can be partof an electronic engine control. The electronic engine control can beconfigured to determine the amount of fuel, ignition timing and otherparameters that each motor 354,356 needs to keep running. This can beaccomplished by using input values (e.g. engine speed) calculated fromsignals coming from sensors, such as a crankshaft position sensor, whichmonitor each motor 354,356. The electronic engine control can comparethe input values and adjust operation of the motors 354,356 (e.g.,adjust spark timing of each motor) to ensure that the output shafts370,372 are turning at the same rate. As schematically depicted in FIG.10, and according to another aspect, the timing assembly can be a loadsensor control. The load sensor control can convert the amount of airdrawn into each motor 354,356 into a voltage signal, which can then beused to calculate engine load. The engine loads of the motors 354,356can be compared and operation of the motors can be controlled to againensure that the output shafts 370,372 are turning at the same rate.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also thatvarious presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims.

What is claimed is:
 1. A device comprising: an implement configured tobe driven; and a first motor and a second motor, each motor including arotational output shaft and a transmission assembly connected to theoutput shaft, the output shafts of the first and second motor beingcoupled together by the transmission assemblies such that the outputshafts turn at the same rate, the first and second motors contributingequally to the driving of the implement.
 2. The device of claim 1,further including a frame for supporting the first and second motors ina front-to-back relationship, the rotational output shaft of each motorbeing aligned generally transverse to a longitudinal length of the atleast one frame.
 3. The device of claim 1, wherein the implement isrotatably connected to the frame via an implement shaft orientedparallel to the outputs shafts of the first and second motors, theimplement shaft having at least one sheave pulley, and the transmissionassembly of the first motor nearest the implement shaft includes a firstsprocket assembly having a first sprocket and a second sprocket, the atleast one sheave pulley of the implement shaft being operably coupled toone of the sprockets of the first sprocket assembly.
 4. The device ofclaim 3, further including a rotatable jack shaft oriented parallel tothe outputs shafts of the first and second motors and to the implementshaft, the jack shaft having a sprocket and at least one sheave pulley,the sprocket being operably connected to the first sprocket of the firstsprocket assembly of the first motor, the at least one sheave pulleybeing operably being connected to the at least one sheave pulley of theimplement shaft.
 5. The device of claim 4, wherein the sprocket of thejack shaft has a diameter approximately twice a diameter of the at leastone sheave pulley of the jack shaft.
 6. The device of claim 4, furtherincluding a first flexible belt having teeth formed along an innersurface thereof, the teeth of the first flexible belt engaging the firstsprocket of the first sprocket assembly and the sprocket of the jackshaft.
 7. The device of claim 4, wherein the jack shaft includes a firstend portion and a second end portion, the first end portion includingthe sprocket and a first sheave pulley and the second end portionincluding a second sheave pulley, and the implement shaft includes afirst end portion and a second end portion, the first end portionincluding a first sheave pulley and the second end portion including asecond sheave pulley, wherein the first sheave pulley of the jack shaftis operably connected to the first sheave pulley of the implement shaftand the second sheave pulley of the jack shaft is operably connected tothe second sheave pulley of the implement shaft.
 8. The device of claim7, further comprising a second flexible belt engaging the first sheavepulley of the jack shaft and the first sheave pulley of the implementshaft, and a third flexible belt engaging the second sheave pulley ofthe jack shaft and the second sheave pulley of the implement shaft. 9.The device of claim 4, further including a tensioner assembly connectedto the frame, the tensioner assembly configured to provide positionaladjustment between the output shaft of the first motor, the jack shaftand the implement shaft.
 10. The device of claim 9, further including asecond frame positioned on the frame, the implement shaft being locatedon the frame, each of the first and second motors and the jack shaftbeing located on the second frame, the tensioner assembly configured toprovide vertical adjustment between the frame and the second frame. 11.The device of claim 3, wherein the transmission assembly of the secondmotor includes a second sprocket assembly having a first sprocket and asecond sprocket, one of the sprockets of the second motor being operablyconnected to the second sprocket of the first motor, and furthercomprising a belt assembly operably connected to the other sprocket ofthe second motor, the belt assembly adapted to power an associatedhydrostatic motor for propelling the device.
 12. The device of claim 11,further including a fourth flexible belt having teeth formed along aninner surface thereof, the teeth of the fourth flexible belt engagingthe second sprocket of the first sprocket assembly of the first motorand the one sprocket of the second sprocket assembly of the secondmotor.
 13. The device of claim 11, wherein each of the first and secondsprockets of the first sprocket assembly of the first motor and the onesprocket of the second sprocket of the second motor have approximatelyequal diameters.
 14. The device of claim 1, further comprising a timingassembly configured to ensure that the output shafts of the first andsecond motors turn at approximately the same rate, the timing assemblybeing part of an ignition system of each of the first and second motors.15. The device of claim 1, wherein the device is a concrete saw and theimplement is a saw blade.
 16. A concrete saw comprising: a generallyrectangular frame having a front end, a read end and a longitudinallength; a first motor and a second motor supported by the frame, eachmotor including a rotational output shaft aligned generally transverseto the longitudinal length of the frame and a sprocket assemblyconnected to the output shaft, the output shafts of the first and secondmotors being coupled together by the sprocket assemblies such that theoutput shafts turn at approximately the same rate, the first and secondmotors contributing equally to the driving of a saw blade the saw bladerotatably connected to the frame via a saw blade shaft oriented parallelto the outputs shafts of the first and second motors, the saw bladeshaft having at least one sheave pulley; and a rotatable jack shaftoriented parallel to the outputs shafts of the first and second motors,the jack shaft having a sprocket and at least one sheave pulley, thesprocket being operably connected to one of the sprocket assemblies ofthe first and second motors, the at least one sheave pulley beingoperably connected to the at least one sheave pulley of the saw bladeshaft.
 17. The concrete saw of claim 16, wherein the first and secondmotors are positioned in a front-to-back relationship on the frame. 18.The concrete saw of claim 16, further including a second framepositioned on the frame and a tensioner assembly connected to the frameand second frame, the saw blade shaft being located on the frame, eachof the first and second motors and the jack shaft being located on thesecond frame, the tensioner assembly being configured to providevertical adjustment between the frame and the second frame.
 19. Theconcrete saw of claim 16, further comprising a timing assembly operablyconfigured to ensure that the output shafts of the first and secondmotors turn at approximately the same rate, the timing assembly beingpart of an ignition system of each of the first and second motors. 20.The concrete saw of claim 16, further comprising a plurality of flexiblebelts for interconnecting the sprocket assemblies of the first andsecond motors, the at least one sheave pulley of the saw blade shaft,and the sprocket and at least one sheave pulley of the jack shaft.